Field of the Invention
The present invention relates to an image processing apparatus, an information processing method, and a non-transitory computer-readable medium.
Description of the Related Art
Heretofore, apparatuses which scan documents and which store the resulting data as electronic data are line scanners using line sensors to capture images, and camera scanners using two-dimensional imaging sensors to capture images. In particular, in the case of a camera scanner in which a camera is disposed above a document board and which captures an image of a document which is put on the document board and whose surface faces upward, unlike a line scanner, no closed space is present between the camera and the document board. Therefore, the install position of the camera scanner may cause an adverse effect produced by incident light from the outside or illumination light.
Therefore, to improve the image quality of image data obtained from a photographed document, a camera scanner needs to perform calibration in accordance with the installation environment, and needs to correct the photographed document data by using obtained correction parameters.
Attachment or the like of dust or dirt occurs as the document board is used. When a document is put on the document board, an adhered substance, such as dust or dirt, does not affect the photographed document data because the adhered substance is hidden under the document. In contrast, an adverse effect produced by incident light from the outside or illumination light does not change even when a document is put. Therefore, in a calibration process in which the document board is photographed to obtain correction parameters, the camera scanner needs to differentiate an adverse effect produced by an adhered substance, such as dust or dirt, from that produced by incident light from the outside or illumination light, and the adverse effect produced by an adhered substance, such as dust or dirt, needs to be removed. An image scanning apparatus disclosed in Japanese Patent Laid-Open No. 2007-110179 identifies whether occurrence of uneven image density is caused by dust attached to a light path or by uneven sensitivity of image sensors, and performs an adequate process.
However, the image scanning apparatus disclosed in Japanese Patent Laid-Open No. 2007-110179 employs a method of identifying an adverse effect produced by dust attached to a light path, by specifying black in an image. Therefore, a problem arises in which the image scanning apparatus has difficulty in making correct identification when the color of an adhered substance in the image is other than black.